feat(schedule): support KOL subscription targets and random time windows

Extend schedule tasks to dispatch KOL subscription prompts in addition
to prompt rules, add daily/weekly scheduling with fixed or random time
windows, and track dispatch outcomes (last run, status, consecutive
failures).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/internal/tenant/domain/schedule_task.go

@@ -3,24 +3,36 @@ package domain
 import "time"
 
 type ScheduleTask struct {
-	ID                int64
-	TenantID          int64
-	WorkspaceID       *int64
-	OperatorID        *int64
-	PromptRuleID      int64
-	BrandID           *int64
-	Name              string
-	CronExpr          string
-	AutoPublish       bool
-	PublishAccountIDs []string
-	CoverAssetURL     *string
-	CoverImageAssetID *int64
-	EnableWebSearch   bool
-	GenerateCount     int
-	StartAt           *time.Time
-	EndAt             *time.Time
-	NextRunAt         *time.Time
-	Status            string
-	CreatedAt         time.Time
-	UpdatedAt         time.Time
+	ID                   int64
+	TenantID             int64
+	WorkspaceID          *int64
+	OperatorID           *int64
+	TargetType           string
+	PromptRuleID         *int64
+	SubscriptionPromptID *int64
+	BrandID              *int64
+	Name                 string
+	CronExpr             string
+	ScheduleKind         string
+	ScheduleDays         []string
+	ScheduleTimeMode     string
+	RandomWindowStart    string
+	RandomWindowEnd      string
+	GenerationInput      map[string]interface{}
+	AutoPublish          bool
+	PublishAccountIDs    []string
+	CoverAssetURL        *string
+	CoverImageAssetID    *int64
+	EnableWebSearch      bool
+	GenerateCount        int
+	StartAt              *time.Time
+	EndAt                *time.Time
+	NextRunAt            *time.Time
+	LastRunAt            *time.Time
+	LastDispatchStatus   *string
+	LastDispatchError    *string
+	ConsecutiveFailures  int
+	Status               string
+	CreatedAt            time.Time
+	UpdatedAt            time.Time
 }